Sex.
I never really thought about connections between sex and my childhood, but my therapist has pointed out that it was never presented as anything warm and fuzzy, caring, or attached to emotions.
My father told stories... All about how to "melt the elastic off panties" with different drinks, dating ideas, how to manipulate and objectify women, stories of his own escapades. His presentations were fully scientific or horribly sexist. Even about the "best moaner ever" a friend of his was sleeping with in college, or how he rescued a girl from a violent friend's bed, since he always woke up swinging.
My mother... Was probably just sexually frustrated by the time I came along. She enjoyed laying around naked, and never wanted anyone upset about it. But after a certain age, seeing my mother's bush was not exactly something I cared to do. She would try to nibble on my earlobes, because my sister had liked it when she was little. I always thought it was weird, and wanted her to get away. Or she'd want to leave hickies on my wrist, because she LOOOOOOVED giving a good hickie, and my father would never let her (to be honest, once you have the start of a career, I agree). I almost hit her in the face trying to stop her.
By high school, my mother would complain to me about her sexual frustrations, how my father's health problems made sex difficult, and how he was "so f*cking sensitive about it" when she complained. Then it was about regrets in marrying my horrible father, how another man asked her to run away with him & she should've gone... How she tried to give my father a lap dance & he started telling her she was doing it wrong.
Then it was complaints about my father's small penis, his weight, his yeast infections. And when they did have sex, there was no attempt to veil it. They simply put a deadbolt on their door when we were kids so no one could interrupt.